Sneaking out to have sex tonight, I'm 18

I just wanted to rant, but I'm fucking 18. I shouldn't have to sneak around my grandparents in order to have sex, I'm not a minor anymore. God love them but they are so nosey and I'm sexually frustrated lmao. I mean it's not like I'm 15 with a curfew, if I wanna do grown things I should be able to without sneaking around. I know it's their roof but for crying out loud. I'm waiting until they pass out tn to sneak out, wish me good luck.